I know Starbucks uses RO water in their coffee. Its supposed to allow for greater extraction of the aromatic oils that give coffee its taste.

As for medical concerns, I know that there were a lot of problems with carbon canisters that are hooked up to your sink. Bacteria grow really well in a carbon bed. Most of the new ones have some silver impregnated in the carbon to limit bacterial growth. Medical grade RO water such as used for hemodialysis is treated with UV before use.

Gary